Tampons, particularly so-called tube tampons, have recently become an important segment in the sanitary protection market. These tube tampons are bullet shaped and inserted by means of two tubes which telescope with respect to each other. The inner or plunger tube abuts the flat bottom of the tampon and is used to expel the tampon through the leading or insertion end of the outer tampon tube. This leading end may be open or may have some closure which is generally petal shaped and slit so that when force is applied the petals will be pushed outward and away from the leading edge of the tampon as it is expelled. The outer tampon tubes have an area at the opposite end for gripping so that the user braces two fingers against this finger gripping area of the outer tube while exerting pressure against the end of the inner tube opposite the tampon abutment end to begin and complete the expulsion and insertion process. Various means for forming this finger grip on the outer tube have been provided including rings of increased circumference and necked-in finger gripping portions as shown for example in U.S. Pat. No. 3,409,011. Outer tubes with necked in finger gripping portions are apparently the most satisfactory in performance.
Both inner and outer tampon tubes are made of either molded thermoplastic material, cardboard or cardboard like products. When outer tampon tubes are made with a necked-in portion regardless of whether the tubes are made from thermoplastic material or cardboard, is difficult to provide uniform inner and outer diameter in the necked-in tube portion. This nonuniform wall thickness is unsightly at the external wall portions of the tube. More importantly, however, the uneven inner wall profile resulting from this compression is likely to inhibit the expulsion function because of the uneven profile abutting the inner tube. In other words, the inner tube may not travel axially as expulsion occurs therefore distorting the direction of the expulsion force as applied to the bottom of the tampon making it difficult to remove from the outer tube. It will also enhance the possibility for improper directional insertion within the vagina.